In this third edition of our universal apps series I’m going to show you how the back end of the app works. This is actually the server-side script that will give us all information we need to be able to display a list of all post on The Developer Source in our universal app.

First we’ll have a look at the RSS feed of The Developer Source from where we’ll retrieve the needed information. You can see a live preview of our RSS feed right here.

We can see all sorts of information on this page, we can see things like the Title of all posts, a short description and the date of when the post got published. But in the code of the RSS file there is a lot more information. We can also find information like who wrote the post, or a link to the post itself.

You can see the code of the RSS feed by right-clicking on the page and selecting ‘View page source’, you can see the difference below.

Now we know how the RSS feed works we can start with converting it to JSON, we’ll use php for that. We use JSON because it’s a universal way of serving data to a client application. A lot of API’s use JSON formatting, so we’ll do the same.

With the following php code we extract the needed data from the RSS feed and output it as a JSON string.